Proceedings of the European Workshop in La Grande Motte, Herault, France 15th - 18th May, 1984. It contains papers a) the structural and dynamic properties of protonic electrolytes; b) the phenomonological and physical interpretation of complex-admittance measurements; and c) device design and materials specifications. Furthermore, a review of present and potential uses of solid-state protonic conductors for fuel cells, batteries, sensors and other applications is included.